Assessing the Discriminatory Power of Noninvasive Quantification of Myocardial End-Diastolic Wall Stress

Abstract

Analysis of the forces and stresses developed in the wall of the LV (mechanics and performance of the myocardium) provide the clinician with more advanced diagnostic techniques. The aim of this study was assessing the discriminatory Power of noninvasive quantification of myocardial end-diastolic wall stress.Fifty-nine CAD patients (29 with significant and 30 with moderate LAD stenosis in proximal part) and 35 healthy subjects evaluated in this study. The average end-diastolic wall stress (σ ) calculated at LV anterior and interventricular septum wall segments using the formula proposed by Deanda et al [15] with taking into account regional wall thickness (h), meridional ( R φ ) and circumferential ( R θ ) regional radii of curvature at the equator of each segment and noninvasive LVEDP. In this study; regional wall thickness and radii of curvature measured from the echocardiographic 2D apical four and two-chamber views and noninvasive LVEDP estimated with lateral early-diastolic color- TDI annular velocity, combined with mitral early velocity by pulsed Doppler echocardiography (lateral E/E a ratio) by averaging three consecutive heart beats. Receiver operating characteristic (ROC) curve and the area under the ROC curve used as an effective method of evaluating the performance of diagnostic tests and measure of the discriminatory power of a diagnostic test, respectively. Comparison of the calculated enddiastolic myocardial wall stress (kdyn/cm2) between patients with significant and moderate coronary stenosis and healthy subjects showed that there are statistically significant differences in all anterior and septum wall segments. The apex segments of anterior and septum walls were the most accurate indexes of induced ischemia (discriminatory power 0.81 and 0.78, respectively) compared to mid (discriminatory power 0.78 and 0.74, respectively) and base segments (discriminatory power 0.73 and 0.69, respectively). Our results bring up noninvasive end-diastolic myocardial wall stress in CAD patients as an important index in evaluating myocardial performance.